Packing assembly for a pump

ABSTRACT

A header ring for use in a stuffing box comprising an annular body portion of an elastomeric material, an annular radially inward projecting sealing lip portion formed on said body portion and an annular, axially facing pedestal portion formed on said body portion, said pedestal portion defining an annularly extending radially inwardly facing pedestal surface, the sealing lip portion defining an annularly extending, radially inward facing sealing surface, the sealing surface and the pedestal surface forming a juncture, at least a portion of the pedestal portion adjacent the juncture and forming the pedestal surface and at least a portion of the sealing lip portion adjacent the juncture and forming a portion of the sealing surface being comprised of a layer of reinforced elastomeric material bonded to the body portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.14/459,869 filed Aug. 14, 2014, which is a Continuation of U.S. patentapplication Ser. No. 13/954,672 filed Jul. 30, 2013 now abandoned, whichis a Continuation of U.S. patent application Ser. No. 13/440,585, filedApr. 5, 2012 now abandoned, which is a Continuation of U.S. patentapplication Ser. No. 12/347,207, filed Dec. 31, 2008 now abandoned,which claims the benefit of U.S. Provisional Application No. 61/018,538filed on Jan. 2, 2008, the disclosures of which are incorporated hereinby reference for all purposes.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a packing or seal assembly for a pumpand more particularly to a header ring for use in such an assembly.

Description of Prior Art

Piston pumps or plunger pumps are positive displacement pumps and arecommonly used in environments where the fluids which are being handledpose problems such as high temperatures, viscous and very viscous mediaor solids-charged liquids.

One important use of plunger pumps is in the oil and gas industry andparticularly in the drilling, completion and/or stimulation of oil orgas wells. In these applications, it is common to employ solids ladendrilling fluids, e.g., muds, cement slurries, fracturing slurries, acidsand the like, which frequently must be pumped under high pressure intothe well. This is particularly true in the case of completion and/orstimulation procedures where very high pressures are employed and thefluids being handled are typically slurries which make the fluids highlyabrasive because of the large solids content of the slurries.

As is well known in the art, positive displacement reciprocatingplunger-type pumps in this environment pose difficult sealing problemsat the high pressure end where the abrasive fluid must be prevented fromleaking between the reciprocating plunger and the cylinder or housingwithin which it reciprocates.

Although a variety of sealing or packing systems are known to sealbetween the reciprocating plunger and the cylinder, a typical sealarrangement comprises one or more V-shaped or Chevron packing rings withvarious male and female adaptor rings at the forward and rearward endsof the packing assembly. To ensure sealing between the plunger and thecylinder, the sealing assembly can be placed under compression by anadjusting ring, spring loading, etc.

A typical packing assembly of the type under discussion includes aheader ring which is typically made of an elastomeric material. Theheader ring can be constructed of a homogeneous elastomeric material oran elastomeric material containing layers of cloth or other reinforcingtype materials. It is also known to cover certain surfaces of the headerring, particularly the so-called rearward surfaces with a reinforcingfabric.

It has been found that, with respect to the header ring, failure of thesealing assembly primarily occurs due to a phenomena known as“nibbling.” This nibbling phenomenon can be best understood by referenceto FIGS. 1-4 which depict prior art construction for header rings of thetype under consideration. FIG. 1 depicts a typical homogeneouselastomeric header ring shown as 10. As can be seen in FIG. 1, headerring 10 is made of a homogeneous elastomeric material and comprises anannular body portion 12.

Integrally formed with body 12, is an annular, radially inwardlyprojecting wiping lip 14, an annularly extending, axially facing bead16, an annular pedestal portion 18. Header ring 10 includes a forwardlyfacing, annularly extending planar surface 20, an annularly extending,radially outwardly facing cylindrical surface 22, an annularlyextending, radially inwardly facing cylindrical surface 24 and aradially inwardly facing convex sealing surface 26, surfaces 24 and 26being adjoined at an annularly extending juncture 28.

Referring now to FIG. 2, the header ring 10 is shown after use and aftera portion of the header ring has been nibbled out. As can be seen, thenibbled out area indicated at 30 comprises a portion of header ring 10formed by intersecting surfaces 24 and 26. More specifically, it can beseen that the juncture 28 shown in FIG. 1 between surfaces 24 and 26 hasbeen gouged out due to the nibbling effect.

FIGS. 3 and 4 depict another prior art header ring, FIG. 3 depicting theheader ring in its original or undamaged state, FIG. 4 depicting theheader ring of FIG. 3 following use and damage as a result of nibbling.The header ring 10A shown in FIG. 3 has a body portion 32 comprised offirst body section 34 and second body section 36. Section 36 of bodyportion 32 comprises a fabric or fiber reinforced material while portion34 is formed of a homogeneous elastomeric material construction. As inthe case of header ring 10, there is an annular pedestal 38, an annularbead 40 and an annular sealing lip 42. FIG. 4 shows the header ring 10Aof FIG. 3 which has been damaged due to nibbling and once again thenibbling has occurred at the juncture 46 between radially inwardlyfacing cylindrical wall 43 and radially inwardly facing surface 45.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a header ring for use in apacking or seal assembly between a reciprocating, cylindrical member anda cylindrical wall of a housing in which the cylindrical memberreciprocates.

In one aspect, the header ring of the present invention has an annularlyextending body portion, at least a portion of which comprises anelastomeric material, an annular pedestal portion formed on said bodyand having an annular, radially inwardly facing pedestal surface, aradially inwardly facing, annularly extending sealing lip formed on saidbody and having a radially inwardly facing sealing surface, at least aportion of the pedestal portion forming the pedestal surface and an atleast a portion of the sealing lip forming at least a portion of thesealing surface being comprised of a layer of fabric reinforcedelastomeric material.

In another aspect of the present invention, there is provided a sealingassembly for sealing between a cylindrical movable member and a housinghaving a cylindrical bore in which the cylindrical member reciprocates,the sealing assembly including a header ring as described above.

The foregoing objects, features and advantages of the present invention,as well as others, will be more fully understood and better appreciatedby reference to the following drawings, specification and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a prior art header ring prior toinstallation.

FIG. 2 is a cross-sectional view of the header ring of FIG. 1 which hasbeen damaged by nibbling.

FIG. 3 is a cross-sectional view of another type of prior art headerring prior to installation.

FIG. 4 is a cross-sectional view of the header ring of FIG. 3 which hasbeen damaged by nibbling.

FIG. 5 is a cross-sectional view of one embodiment of the header ring ofthe present invention.

FIG. 6 is a cross-sectional view of another embodiment of the headerring of the present invention.

FIG. 7 is a cross-sectional view of another embodiment of the headerring of the present invention.

FIG. 8 is a schematic view, partly in section, of a sealing assemblyaccording to the present invention in the stuffing box of a plungerpump.

FIG. 9 is an enlarged view of the circled portion of the header ringshown in FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to FIG. 5, the header ring 50 comprises an annular bodyportion 52, an annular axially extending pedestal 53, an annular,axially extending bead 56, distal the pedestal 53, and a radiallyinwardly facing, annularly extending sealing lip 58. As can be seen,body 52, bead 56, pedestal 53 and sealing lip 58 are integrally formed,for the most part, of a homogeneous, elastomeric material. However, aportion 60 of the pedestal 53 forming the radially inwardly facingcylindrical surface 61 and the portion 62 of the sealing lip 58 forminga portion of sealing surface 64 is comprised of a layer of reinforced,elastomeric material, bonded to the homogeneous elastomeric material ofthe remainder of header ring 50. As seen, the portions 60 and 62 extendover the juncture 63 of surfaces 61 and 64. When in the relaxed state asshown in FIG. 5, the fabric reinforced sections 60 and 62, whenadjoined, are generally L-shaped when viewed in transversecross-section.

FIG. 6 shows another embodiment of the present invention wherein theheader ring 68 has an annular body portion 70 which is primarily made ofa homogeneous elastomeric material. The header ring 68 has an annular,radially outwardly facing cylindrical surface 72. Bonded to thehomogeneous elastomeric portion of body 70 is an annular layer 74 of afabric reinforced elastomer, the layer 74 covering the surfaces of thepedestal 76, the sealing lip 78, the bead 80 and portions of the forwardand rearward portions of the body 70 forming surface 72. As in the caseof the embodiment shown in FIG. 5, the portions of the pedestal 76 andsealing lip 78 forming juncture 82 between the pedestal 76 and thesealing lip 78 is formed of a layer of fabric reinforced elastomericmaterial forming adjoining surfaces 82A and 82B.

Turning to FIG. 7, there is shown another embodiment of the presentinvention, wherein the header ring, shown generally as 88, has a body89, the core 90 of which is comprised of an elastomeric material, aportion of annular pedestal 92 and a portion of annular sealing lip 94.Unlike the embodiment shown in FIG. 6, in the embodiment shown in FIG.7, the reinforced fabric layer 96 completely encapsulates or surroundsthe core 90 of body portion 89.

FIG. 8 depicts a typical sealing assembly 101 for use in a stuffing box,shown generally as 100, of a plunger-type pump employing a header ringof the present invention. Stuffing box 100 comprises a housing 102having a bore 104 extending therethrough, bore 104 defining acylindrical surface 103. Housing 102 also has a shoulder portion 108.Movably, e.g., reciprocally, positioned in bore 104 is a plunger, pistonor shaft 106. Sealing assembly 101 comprises an annular gland 105, anannular header ring 110, an-annular, first seal ring 112, and anannular, second seal ring 114. The sealing assembly 101 also includes atop, annular adaptor ring 116 and an annular bushing 118. As can beseen, header ring 110 forms a wiper ring at the high pressure end of thesealing assembly 101, its primary function being to preventabrasives/solids from entering the region where the seal rings 112 and114 are positioned and thereby prevent excessive wear on seal rings 112and 114. It is also to be noted that, as shown in FIG. 8, header ring110 no longer has the shape shown in, for example, FIG. 5 since theradially inwardly extending sealing lip 111 has been compressed toeffect sealing between the plunger 106 and the housing 102, thecylindrical surface 103 being in sealing engagement with an annular,radially outwardly facing surface 109 of the compressed header ring 110which is generally cylindrical.

Referring now to FIG. 9, there is shown an enlargement of the circledportion of FIG. 8. As an example of the present invention, header ring110 is constructed essentially the same as the header ring shown in FIG.5 having a generally L-shaped, annularly extending reinforcing sectionor layer 120 that bridges the juncture 122 between the surface ofsealing lip 124 and the surface of pedestal 126.

While packing assembly 101 has been shown as containing two seal ringsof the chevron or V-shaped type, it will be appreciated that dependingupon the use to which the plunger pump is subjected, fewer or moresealing rings can be employed. It will also be seen that the annularbead 119 of header ring 110 is nested in the annularly extending,axially facing groove in seal ring 112 so as to anchor seal ring 112 tothe header ring 110. It will be appreciated that the seal rings 112 and114 can be constructed of various materials and have various shapes, theonly provision being that they have sufficient resiliency to effectsealing between the housing 102 and plunger 106. Generally speaking,components such as annular bushing 118, top adaptor 116, and annulargland 105 are made of a metallic material, e.g., brass.

The packing assembly 101 can be energized by header ring 110 and can bemade to be adjustable by techniques well known in the art. If, howeverthe packing assembly 101 is preloaded, care must be taken to ensure thatthe correct amount of preload is employed to prevent movement of thesealing assembly in the housing or stuffing box to prevent excessivewear on the sealing assembly. In this regard, if there is too littlepreload the packing will move in the housing wearing both the ID and ODof the seal rings as well as the header ring causing premature wear andin extreme cases causing wear in the stuffing box resulting in expensiverepair or refurbishment. On the other hand, if the packing assembly isadjusted with too little preload, high friction forces cause acceleratedwear of the header ring and the seal rings with premature failure.

The homogeneous elastomeric core of the header ring of the presentinvention can be made from a number of different natural or syntheticrubbers as, for example, nitrile or butadiene rubber, with a desireddegree of hardness again depending upon the use to which the plungerpump is exposed. Likewise, the elastomeric portions of the seal rings112 and 114 can be of various rubbers with desirable hardness. Asindicated, the seal rings, e.g., seal rings 112 and 114, can bereinforced with fabric, can be homogeneous elastomeric materials, canhave anti-extrusion portions, etc.

Sections 61 and 62 forming an anti-nibbling section, as seen in FIG. 5indicated, are generally a fabric reinforced rubber, synthetic ornatural. The term fabric as used with respect to the anti-nibbling wearsection of the various embodiments of the present invention is used inthe broadest sense and includes any cloth or cloth-like structure madeby any technique such as knitting, weaving or felting of fibers ofnatural or synthetic materials as well as mixed fibers and includes,without limitation, fibers of cotton, nylon, polyester, polyesterblends, aramid fibers, fiberglass fibers or any combination thereof.

The foregoing description and examples illustrate selected embodimentsof the present invention. In light thereof, variations and modificationswill be suggested to one skilled in the art, all of which are in thespirit and purview of this invention.

The invention claimed is:
 1. A header ring comprising: an opening; aradially inwardly facing annularly extending sealing lip adjacent theopening; a radially inwardly facing cylindrical surface adjacent theopening; an annular radially outwardly facing cylindrical surfaceopposite the opening; a first annular radially extending surfaceextending between the radially inwardly facing cylindrical surface andthe annular radially outwardly facing cylindrical surface; a secondannular axially extending surface extending between the annular radiallyoutwardly facing cylindrical surface and the radially inwardly facingannularly extending sealing lip; an axially extending annular beadopposite the first annular radially extending surface, the bead beingadjacent the second annular axially extending surface and the radiallyinwardly facing annularly extending sealing lip; and fabric reinforcedelastomeric material covering at least the radially inwardly facingannularly extending sealing lip and the radially inwardly facingcylindrical surface.
 2. The header ring of claim 1, wherein the fabricreinforced elastomeric material forms a barrier blocking operationalnibbling away of the header ring at a junction of the radially inwardlyfacing annularly extending sealing lip and the radially inwardly facingcylindrical surface.
 3. A header ring comprising: an opening; a radiallyinwardly extending first annular surface adjacent the opening, whereinthe radially inwardly extending first annular surface has a portionfacing in a first direction; an axially extending second annular surfaceopposite the opening; a radially extending third annular surface facingin the first direction and extending between the first annular surfaceand the second annular surface; a fourth annular surface facing in asecond direction, the second direction being opposite to the firstdirection, and extending between the second annular surface and theradially inwardly extending first annular surface; an axially extendingannular bead facing in the second direction and opposite the thirdannular surface, the bead being adjacent the first annular surface; andfabric reinforced elastomeric material covering at least the surfaces ofthe header ring facing in the first direction.
 4. The header ring ofclaim 3, wherein the fabric reinforced elastomeric material covers theradially inwardly extending first annular surface, the axially extendingsecond annular surface, the radially extending third annular surfacefacing in the first direction, and the fourth annular surface facing inthe second direction.
 5. The header ring of claim 3, wherein the fabricreinforced elastomeric material covers the radially inwardly extendingfirst annular surface, the axially extending second annular surface, theradially extending third annular surface facing in the first direction,the fourth annular surface facing in the second direction and theaxially extending annular bead facing in the second direction.
 6. Aheader ring comprising: an opening; and a resilient body, comprising: aradially inwardly extending first annular portion adjacent the opening,the radially inwardly extending first annular portion having a portionfacing in a first direction; an axially extending second annular portionadjacent the opening; an axially extending third annular portionopposite the opening; a radially extending fourth annular portion facingin the first direction and extending between the second and thirdannular portions; a fifth annular portion facing in a second direction,the second direction being opposite to the first direction, andextending between the third annular portion and the first annularportion; an axially extending annular bead facing in the seconddirection and opposite the fourth annular portion, the bead beingadjacent the first annular portion; and fabric reinforced elastomericmaterial covering at least the portion of the radially inwardlyextending first annular portion facing in the first direction and theaxially extending second annular portion.
 7. The header ring of claim 6,wherein the resilient body is formed substantially entirely from ahomogeneous elastomeric material.
 8. The header ring of claim 7, whereinthe homogeneous elastomeric material is natural rubber or syntheticrubber.
 9. A header ring comprising: an opening; a resilient body,comprising: a radially inwardly extending first annular portion adjacentthe opening; an axially extending second annular portion adjacent theopening; an axially extending third annular portion opposite theopening; a radially extending fourth annular portion extending betweenthe second and third annular portions; a fifth annular portion extendingbetween the third annular portion and the first annular portion; andfabric reinforced elastomeric material entirely encapsulating theresilient body and defining the exterior surface thereof.
 10. The headerring of claim 9, wherein the fabric reinforced elastomeric materialforms a barrier blocking operational nibbling away of the header ring atthe junction of the first and second annular portions thereof.
 11. Theheader ring of claim 9, wherein the resilient body is formedsubstantially entirely from a homogeneous elastomeric material.
 12. Theheader ring of claim 11, wherein the homogeneous elastomeric material isnatural rubber or synthetic rubber.
 13. The header ring of claim 9,wherein the header ring further comprises a rearward facing axiallyextending annular bead opposite the fourth annular portion, the beadbeing adjacent the first annular portion.
 14. A header ring comprising:a body that does not include layers of fabric, comprising an annular,radially inwardly projecting portion from which an annular pedestalportion, disposed on the opposite side of the header ring, axiallyextends, the radially inwardly projecting portion and the annularpedestal portion being formed of an elastomeric material, the pedestalportion having an annular interior side surface which is radiallyoutwardly offset relative to the radially inner circumference of theradially inwardly projecting portion and forms with the radiallyinwardly projecting portion an annular juncture area therebetween,wherein the entire body of the header ring is covered by reinforcedelastomeric material which defines the exterior surface of the headerring.
 15. The header ring of claim 14 wherein the reinforced elastomericmaterial is fabric-reinforced elastomeric material.
 16. The header ringof claim 14 wherein the elastomeric material is natural rubber orsynthetic rubber.